Part of Lesson Plan: **Ingredient 1: Fuel (updated) by Thomas Dougherty

Activity Overview / Details

Next we don our safety glasses and migrate to the work bench to transfer this lesson to an actual carburetor.  I have a small engine carburetor on the bench which is hooked to a small shop vacuum with a piece of 1 1/2 clear plastic tubing (duct tape works well). 

The fuel line is connected to a squeeze bottle containing water and an entire bottle of blue food coloring.  When the vacuum is turned on, air is drawn through the carburetor and students are able to see the inside of the clear tube turn blue.  As the throttle valve is opened, the amount of air and fuel going through the tube increases and the tube turns a darker blue.  As the mixture screws are turned the air/fuel ratio changes and the color changes with it.  Back to the classroom!